Field of the Invention
The present invention relates to a shutter unit, a lithography apparatus, and a method of manufacturing an article.
Description of the Related Art
In the manufacture of semiconductor devices, a reduction projection exposure apparatus that reduces a pattern of an original by a reduction projection lens and projects the reduced pattern onto a substrate is generally used. In such an apparatus, a process of performing a step movement of an XY stage which is loaded with a substrate and an exposure process are alternately repeated to transfer and print several tens of patterns of the original onto a single substrate.
In recent years, to improve the productivity of the exposure apparatus, attempts have been made to shorten the exposure cycle time by increasing the opening and closing speed of a shutter which is arranged on the optical path of the exposure light. For example, in Japanese Patent Laid-Open No. 11-233423, there is proposed an exposure apparatus that uses two rotation shutter members each including a light shielding portion and a light transmissive portion to switch between irradiation and non-irradiation of a substrate with light by controlling the rotation of the two shutter members. According to this arrangement, the shutter members can be reduced in size and weight, thereby allowing the shutter operation speed to be increased.
On a related note, since a shutter is driven to open and close, there is a gap around a shutter member. Hence, in some cases, it is impossible to completely shield the light because the exposure light can pass the shutter unit upon being reflected repetitively by this gap, and a resist applied on a substrate may be undesirably exposed to light.